Go语言视频零基础入门到精通

五菱

11. 在java上的HTTP代理设置

2. System.getProperties().put("http.proxyHost",
3. "someProxyURL");   
4. System.getProperties().put("http.proxyPort",
5. "someProxyPort");   
6. System.getProperties().put("http.proxyUser",
7. "someUserName");   
8. System.getProperties().put("http.proxyPassword",
9. "somePassword");
11. System.getProperties().put("http.proxyHost",
12. "someProxyURL");
13. System.getProperties().put("http.proxyPort",
14. "someProxyPort");
15. System.getProperties().put("http.proxyUser",
16. "someUserName");
17. System.getProperties().put("http.proxyPassword",
18. "somePassword");

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12. java Singleton 例子

2. Read this article for more
3. details.
4. Update: Thanks Markus for the comment. I have updated the code and
5. changed it to
7. more robust implementation.
9. public class SimpleSingleton {   
10. private static SimpleSingleton singleInstance =  new SimpleSingleton
11. ();   
12. //Marking default constructor
13. private   
14. //to avoid direct
15. instantiation.   
16. private SimpleSingleton()
17. {   
18. }   
19. //Get instance for class SimpleSingleton   
20. public static SimpleSingleton getInstance() {   
21. return
22. singleInstance;   
23. }   
24. }
25. public class SimpleSingleton {
26. private static SimpleSingleton
27. singleInstance =  new SimpleSingleton();
28. //Marking default constructor private
29. //to avoid direct
30. instantiation.
31. private SimpleSingleton() {
32. }
33. //Get instance for class SimpleSingleton
34. public static
35. SimpleSingleton getInstance() {
36. return singleInstance;
37. }
38. }
39. One more implementation of
40. Singleton class. Thanks to Ralph and Lukasz Zielinski
41. for pointing this out.
43. public enum SimpleSingleton {   
44. INSTANCE;   
45. public void doSomething()
46. {   
47. }   
48. }   
49. //Call the method from Singleton:   
50. SimpleSingleton.INSTANCE.doSomething();
51. public enum SimpleSingleton {
52. INSTANCE;
53. public void
54. doSomething() {
55. }
56. }
57. //Call the method from Singleton:
58. SimpleSingleton.INSTANCE.doSomething();

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13. 在java上做屏幕截图

2. Read this article for more details.
4. import
5. java.awt.Dimension;   
6. import java.awt.Rectangle;   
7. import java.awt.Robot;   
8. import java.awt.Toolkit;   
9. import java.awt.image.BufferedImage;   
10. import
11. javax.imageio.ImageIO;   
12. import java.io.File;   
13. ...   
14. public void captureScreen(String fileName)
15. throws Exception {   
16. Dimension screenSize =
17. Toolkit.getDefaultToolkit().getScreenSize();   
18. Rectangle
19. screenRectangle = new Rectangle(screenSize);   
20. Robot
21. robot = new Robot();   
22. BufferedImage image =
23. robot.createScreenCapture(screenRectangle);   
24. ImageIO.write(image, "png", new File(fileName));   
25. }
26.    
27. ...
28. import java.awt.Dimension;
29. import java.awt.Rectangle;
30. import
31. java.awt.Robot;
32. import java.awt.Toolkit;
33. import
34. java.awt.image.BufferedImage;
35. import javax.imageio.ImageIO;
36. import
37. java.io.File;
38. ...
39. public void captureScreen(String fileName) throws Exception {
40. Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize
41. ();
42. Rectangle screenRectangle = new Rectangle
43. (screenSize);
44. Robot robot = new Robot();
45. BufferedImage image = robot.createScreenCapture(screenRectangle);
46. ImageIO.write(image, "png", new File(fileName));
47. }
48. ...

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14. 在java中的文件，目录列表

3. File dir = new File("directoryName");   
4. String[] children = dir.list();   
5. if (children ==
6. null) {   
7. // Either dir does not exist
8. or is not a directory   
9. } else {   
10. for (int i=0; i < children.length; i++)
11. {   
12. // Get
13. filename of file or directory   
14. String filename =
15. children;   
16. }   
17. }   
18. // It is also possible to filter the
19. list of returned files.   
20. // This example does not return any
21. files that start with `.'.   
22. FilenameFilter filter = new
23. FilenameFilter() {   
24. public boolean
25. accept(File dir, String name) {   
26. return !name.startsWith
27. (".");   
28. }   
29. };   
30. children = dir.list(filter);   
31. // The list of files can also be retrieved as File objects   
32. File[] files = dir.listFiles();   
33. //
34. This filter only returns directories   
35. FileFilter fileFilter =
36. new FileFilter() {   
37. public boolean
38. accept(File file) {   
39. return file.isDirectory
40. ();   
41. }   
42. };   
43. files = dir.listFiles(fileFilter);
45. File dir = new File("directoryName");
46. String[]
47. children = dir.list();
48. if (children == null)
49. {
50. // Either dir does not exist or is
51. not a directory
52. } else
53. {
54. for (int i=0; i <
55. children.length; i++)
56. {
57. // Get
58. filename of file or
59. directory
60. String filename = children;
61. }
62. }
63. // It is also possible to filter the list of returned
64. files.
65. // This example does not return any files that start
66. with `.'.
67. FilenameFilter filter = new FilenameFilter()
68. {
69. public boolean accept(File dir,
70. String name)
71. {
72. return !
73. name.startsWith(".");
74. }
75. };
76. children = dir.list(filter);
77. // The list of files can also be retrieved as File
78. objects
79. File[] files = dir.listFiles();
80. // This filter only returns directories
81. FileFilter fileFilter = new FileFilter()
82. {
83. public boolean accept(File file)
84. {
85. return
86. file.isDirectory();
87. }
88. };
89. files = dir.listFiles
90. (fileFilter);

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15. 在java中创建ZIP和JAR文件

2. import java.util.zip.*;   
3. import
4. java.io.*;   
5. public class ZipIt {   
6. public static void main(String args[]) throws IOException
7. {   
8. if (args.length <
9. 2) {   
10. System.err.println("usage: java ZipIt Zip.zip file1 file2 file3");   
11. System.exit
12. (-1);   
13. }   
14. File zipFile = new File(args
15. [0]);   
16. if
17. (zipFile.exists()) {   
18. System.err.println("Zip file already exists, please try another");   
19. System.exit
20. (-2);   
21. }   
22. FileOutputStream fos = new
23. FileOutputStream(zipFile);   
24. ZipOutputStream zos = new
25. ZipOutputStream(fos);   
26. int bytesRead;   
27. byte[]
28. buffer = new byte[1024];   
29. CRC32 crc = new CRC32();   
30. for (int i=1, n=args.length; i < n; i++) {   
31. String name
32. = args;   
33. File file =
34. new File(name);   
35. if (!
36. file.exists()) {   
37. &
38. nbsp;  System.err.println("Skipping: " + name);   
39. &
40. nbsp;  continue;   
41. }
42.    
43. BufferedInputStream bis = new BufferedInputStream(   
44. &
45. nbsp;  new FileInputStream(file));   
46. crc.reset
47. ();   
48. while
49. ((bytesRead = bis.read(buffer)) != -1) {   
50. &
51. nbsp;  crc.update(buffer, 0, bytesRead);   
52. }
53.    
54. bis.close();   
55. // Reset to
56. beginning of input stream   
57. bis = new
58. BufferedInputStream(   
59. &
60. nbsp;  new FileInputStream(file));   
61. ZipEntry
62. entry = new ZipEntry(name);   
63. entry.setMethod(ZipEntry.STORED);   
64. entry.setCompressedSize(file.length());   
65. entry.setSize(file.length());   
66. entry.setCrc(crc.getValue());   
67. zos.putNextEntry(entry);   
68. while
69. ((bytesRead = bis.read(buffer)) != -1) {   
70. &
71. nbsp;  zos.write(buffer, 0, bytesRead);   
72. }
73.    
74. bis.close();   
75. }
76.    
77. zos.close
78. ();   
79. }   
80. }
82. import java.util.zip.*;
83. import java.io.*;
84. public class ZipIt {
85. public static void main(String args
86. []) throws IOException {
87. if
88. (args.length < 2)
89. {
90. System.err.println("usage: java ZipIt Zip.zip file1 file2
91. file3");
92. System.exit(-1);
93. }
94. File zipFile = new File(args
95. [0]);
96. if (zipFile.exists())
97. {
98. System.err.println("Zip file already exists, please try
99. another");
100. System.exit(-2);
101. }
102. FileOutputStream fos = new
103. FileOutputStream(zipFile);
104. ZipOutputStream zos = new ZipOutputStream
105. (fos);
106. int
107. bytesRead;
108. byte[] buffer = new byte
109. [1024];
110. CRC32 crc = new CRC32
111. ();
112. for (int i=1, n=args.length; i
113. < n; i++)
114. {
115. String name
116. = args;
117. File file = new File
118. (name);
119. if
120. (!file.exists())
121. {
122.    System.err.println("Skipping: " +
123. name);
124. &
125. nbsp;   
126. continue;
127. }
128. BufferedInputStream bis = new BufferedInputStream
129. (
130.    new FileInputStream
131. (file));
132. crc.reset();
133. while ((bytesRead = bis.read(buffer)) != -1)
134. {
135.    crc.update(buffer, 0,
136. bytesRead);
137. }
138. bis.close
139. ();
140. // Reset
141. to beginning of input
142. stream
143. bis =
144. new BufferedInputStream
145. (
146.    new FileInputStream
147. (file));
148. ZipEntry entry = new ZipEntry
149. (name);
150. entry.setMethod
151. (ZipEntry.STORED);
152. &
153. nbsp; entry.setCompressedSize(file.length
154. ());
155. entry.setSize(file.length
156. ());
157. entry.setCrc(crc.getValue
158. ());
159. zos.putNextEntry
160. (entry);
161. while ((bytesRead = bis.read(buffer)) != -1)
162. {
163.    zos.write(buffer, 0,
164. bytesRead);
165. }
166. bis.close
167. ();
168. }
169. zos.close();
170. }
171. }
172. 16. Parsing / Reading XML file in java
173. Sample XML file.
178. John
179. B
180. 12
183. Mary
184. A
185. 11
188. Simon
189. A
190. 18
195. John
196. B
197. 12
199. Mary
200. A
201. <
202. AGE>11
204. Simon
205. A
206. 18
208. java code to parse above XML.
210. package net.viralpatel.java.xmlparser;   
211. import java.io.File;   
212. import
213. javax.xml.parsers.DocumentBuilder;   
214. import
215. javax.xml.parsers.DocumentBuilderFactory;   
216. import
217. org.w3c.dom.Document;   
218. import org.w3c.dom.Element;   
219. import org.w3c.dom.Node;   
220. import
221. org.w3c.dom.NodeList;   
222. public class XMLParser
223. {   
224. public void getAllUserNames(String
225. fileName) {   
226. try
227. {   
228. DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();   
229. DocumentBuilder db = dbf.newDocumentBuilder();   
230. File file =
231. new File(fileName);   
232. if
233. (file.exists()) {   
234. &
235. nbsp;  Document doc = db.parse(file);   
236. &
237. nbsp;  Element docEle = doc.getDocumentElement();   
238. &
239. nbsp;  // Print root element of the document   
240. &
241. nbsp;  System.out.println("Root element of the document: "
242. &
243. nbsp;          + docEle.getNodeName
244. ());   
245. &
246. nbsp;  NodeList studentList = docEle.getElementsByTagName
247. ("student");   
248. &
249. nbsp;  // Print total student elements in document   
250. &
251. nbsp;  System.out   
252. &
253. nbsp;          .println("Total
254. students: " + studentList.getLength());   
255. &
256. nbsp;  if (studentList != null && studentList.getLength() > 0)
257. {   
258. &
259. nbsp;      for (int i = 0; i < studentList.getLength();
260. i++) {   
261. &
262. nbsp;          Node node =
263. studentList.item(i);   
264. &
265. nbsp;          if (node.getNodeType()
266. == Node.ELEMENT_NODE) {   
267. &
268. nbsp;            
269. System.out   
270. &
271. nbsp;            
272.          .println
273. ("=====================");   
274. &
275. nbsp;            
276. Element e = (Element) node;   
277. &
278. nbsp;            
279. NodeList nodeList = e.getElementsByTagName("name");   
280. &
281. nbsp;            
282. System.out.println("Name: "
283. &
284. nbsp;            
285.          + nodeList.item(0).getChildNodes
286. ().item(0)   
287. &
288. nbsp;            
289.                
290. ;   .getNodeValue());   
291. &
292. nbsp;            
293. nodeList = e.getElementsByTagName("grade");   
294. &
295. nbsp;            
296. System.out.println("Grade: "
297. &
298. nbsp;            
299.          + nodeList.item(0).getChildNodes
300. ().item(0)   
301. &
302. nbsp;            
303.                
304. ;   .getNodeValue());   
305. &
306. nbsp;            
307. nodeList = e.getElementsByTagName("age");   
308. &
309. nbsp;            
310. System.out.println("Age: "
311. &
312. nbsp;            
313.          + nodeList.item(0).getChildNodes
314. ().item(0)   
315. &
316. nbsp;            
317.                
318. ;   .getNodeValue());   
319. &
320. nbsp;          }   
321. &
322. nbsp;      }   
323. &
324. nbsp;  } else {   
325. &
326. nbsp;      System.exit(1);   
327. &
328. nbsp;  }   
329. }
330.    
331. } catch (Exception e)
332. {   
333. System.out.println(e);   
334. }   
335. }   
336. public
337. static void main(String[] args) {   
338. XMLParser parser = new XMLParser
339. ();   
340. parser.getAllUserNames("c:\\test.xml");   
341. }
342.    
343. }
344. package net.viralpatel.java.xmlparser;
345. import java.io.File;
346. import javax.xml.parsers.DocumentBuilder;
347. import
348. javax.xml.parsers.DocumentBuilderFactory;
349. import org.w3c.dom.Document;
350. import org.w3c.dom.Element;
351. import
352. org.w3c.dom.Node;
353. import org.w3c.dom.NodeList;
354. public class XMLParser {
355. public void getAllUserNames(String fileName) {
356. try
357. {
358. DocumentBuilderFactory dbf =
359. DocumentBuilderFactory.newInstance();
360. DocumentBuilder db =
361. dbf.newDocumentBuilder();
362. File file = new File
363. (fileName);
364. if (file.exists())
365. {
366. Document doc = db.parse
367. (file);
368. Element docEle = doc.getDocumentElement();
369. // Print root element of the
370. document
371. System.out.println("Root element of the
372. document: "
373. + docEle.getNodeName());
374. NodeList studentList = docEle.getElementsByTagName
375. ("student");
376. // Print total student elements in
377. document
378. System.out
379. &nb
380. sp;.println("Total students: " +
381. studentList.getLength());
382. if (studentList != null &&
383. studentList.getLength()
384. > 0) {
385. for (int i = 0; i <
386. studentList.getLength
387. (); i++) {
388. Node node = studentList.item(i);
389. if (node.getNodeType() ==
390. Node.ELEMENT_NODE) {
391. System.out
392.      .println
393. ("=====================");
394. Element e = (Element)
395. node;
396. NodeList nodeList =
397. e.getElementsByTagName
398. ("name");
399. System.out.println("Name:
400. "
401. +
402. nodeList.item(0).getChildNodes().item(0)
403. .getNodeValue());
404. nodeList =
405. e.getElementsByTagName
406. ("grade");
407. System.out.println("Grade:
408. "
409. +
410. nodeList.item(0).getChildNodes().item(0)
411. .getNodeValue());
412. nodeList =
413. e.getElementsByTagName
414. ("age");
415. System.out.println("Age:
416. "
417. +
418. nodeList.item(0).getChildNodes().item(0)
419. .getNodeValue());
420. }
421. }
422. } else
423. {
424. System.exit(1);
425. }
426. }
427. } catch (Exception e)
428. {
429. System.out.println(e);
430. }
431. }
432. public static void main(String[] args) {
433. XMLParser parser = new XMLParser
434. ();
435. parser.getAllUserNames("c:\\test.xml");
436. }
437. }
438. 17.
439. Convert Array to Map in java
440. import java.util.Map;   
441. import
442. org.apache.commons.lang.ArrayUtils;   
443. public class Main
444. {   
445. public static void main(String[] args)
446. {   
447. String[][] countries = { { "United States",
448. "New York" }, { "United Kingdom",
449. "London" },   
450. {
451. "Netherland", "Amsterdam" }, { "Japan", "Tokyo" }, { "France", "Paris" }
452. };   
453. Map countryCapitals =
454. ArrayUtils.toMap(countries);   
455. System.out.println("Capital of Japan is " + countryCapitals.get
456. ("Japan"));   
457. System.out.println("Capital of
458. France is " + countryCapitals.get("France"));   
459. }   
460. }
461. import java.util.Map;
462. import org.apache.commons.lang.ArrayUtils;
463. public class Main {
464. public static void main(String[] args) {
465. String[][]
466. countries = { { "United States", "New York" }, { "United Kingdom",
467. "London" },
468. { "Netherland",
469. "Amsterdam" }, { "Japan", "Tokyo" }, { "France", "Paris" }
470. };
471. Map countryCapitals = ArrayUtils.toMap(countries);
472. System.out.println("Capital of Japan is " +
473. countryCapitals.get("Japan"));
474. System.out.println("Capital of
475. France is " + countryCapitals.get("France"));
476. }
477. }
478. 18. Send Email
479. using java
480. import javax.mail.*;   
481. import
482. javax.mail.internet.*;   
483. import java.util.*;   
484. public void postMail( String recipients[ ], String subject, String message ,
485. String
486. from) throws MessagingException   
487. {   
488. boolean debug = false;   
489. //Set the host smtp address   
490. Properties props = new Properties();   
491. props.put("mail.smtp.host",
492. "smtp.example.com");   
493. // create some
494. properties and get the default Session   
495. Session
496. session = Session.getDefaultInstance(props, null);   
497. session.setDebug(debug);   
498. // create a message   
499. Message msg = new MimeMessage(session);   
500. // set the from and to address   
501. InternetAddress addressFrom = new InternetAddress
502. (from);   
503. msg.setFrom(addressFrom);   
504. InternetAddress[] addressTo = new
505. InternetAddress[recipients.length];   
506. for (int i =
507. 0; i < recipients.length; i++)   
508. {   
509. addressTo = new InternetAddress
510. (recipients);   
511. }   
512. msg.setRecipients(Message.RecipientType.TO,
513. addressTo);   
514. // Optional : You can
515. also set your custom headers in the Email if you Want   
516. msg.addHeader("MyHeaderName", "myHeaderValue");   
517. // Setting the Subject and Content
518. Type   
519. msg.setSubject(subject);   
520. msg.setContent(message, "text/plain");   
521. Transport.send(msg);   
522. }
523. import javax.mail.*;
524. import javax.mail.internet.*;
525. import
526. java.util.*;
527. public void postMail( String recipients[ ], String subject, String message ,
528. String
529. from) throws MessagingException
530. {
531. boolean debug =
532. false;
533. //Set the host smtp address
534. Properties props = new Properties();
535. props.put
536. ("mail.smtp.host", "smtp.example.com");
537. // create some properties and get the default
538. Session
539. Session session = Session.getDefaultInstance(props,
540. null);
541. session.setDebug(debug);
542. // create a message
543. Message msg = new
544. MimeMessage(session);
545. // set the from and to address
546. InternetAddress addressFrom = new InternetAddress(from);
547. msg.setFrom(addressFrom);
548. InternetAddress[] addressTo = new InternetAddress
549. [recipients.length];
550. for (int i = 0; i <
551. recipients.length; i++)
552. {
553. addressTo = new InternetAddress
554. (recipients);
555. }
556. msg.setRecipients
557. (Message.RecipientType.TO, addressTo);
558. // Optional : You can also set your custom headers in the
559. Email if you Want
560. msg.addHeader("MyHeaderName",
561. "myHeaderValue");
562. // Setting the Subject and Content Type
563. msg.setSubject(subject);
564. msg.setContent(message,
565. "text/plain");
566. Transport.send(msg);
567. }
568. 19. Send HTTP
569. request & fetching data using java
570. import java.io.BufferedReader;   
571. import
572. java.io.InputStreamReader;   
573. import java.net.URL;   
574. public class Main {   
575. public static
576. void main(String[] args)  {   
577. try {   
578. URL my_url =
579. new URL("http://www.viralpatel.net/blogs/");&nbs
580. p;
581. BufferedReader br = new BufferedReader(new InputStreamReader
582. (my_url.openStream()));   
583. String
584. strTemp = "";   
585. while(null
586. != (strTemp = br.readLine())){   
587. System.out.println(strTemp);   
588. }   
589. } catch (Exception ex) {   
590. ex.printStackTrace();   
591. }
592.    
593. }   
594. }
595. import java.io.BufferedReader;
596. import
597. java.io.InputStreamReader;
598. import java.net.URL;
599. public class Main {
600. public static void main(String[] args)
601. {
602. try {
603. URL my_url = new URL("http://www.viralpatel.net/blogs/");
604.    BufferedReader br = new BufferedReader(new
605. InputStreamReader(my_url.openStream()));
606. String strTemp =
607. "";
608. while(null != (strTemp = br.readLine()))
609. {
610. System.out.println(strTemp);
611. }
612. } catch (Exception ex) {
613. ex.printStackTrace
614. ();
615. }
616. }
617. }
618. 20. Resize an Array in java
619. /**
620. * Reallocates an array with a new size, and copies the
621. contents
622. * of the old array to the new array.
623. * @param
624. oldArray  the old array, to be reallocated.
625. * @param
626. newSize   the new array size.
627. *
628. @return          A new array with the
629. same contents.
630. */
631. private static Object resizeArray (Object
632. oldArray, int newSize) {   
633. int ldSize =
634. java.lang.reflect.Array.getLength(oldArray);   
635. Class
636. elementType = oldArray.getClass().getComponentType();   
637. Object newArray = java.lang.reflect.Array.newInstance(   
638. elementType,newSize);   
639. int preserveLength = Math.min
640. (oldSize,newSize);   
641. if (preserveLength > 0)
642.    
643. System.arraycopy
644. (oldArray,0,newArray,0,preserveLength);   
645. return
646. newArray;   
647. }   
648. // Test routine for
649. resizeArray().   
650. public static void main (String[] args)
651. {   
652. int[] a = {1,2,3};   
653. a =
654. (int[])resizeArray(a,5);   
655. a[3] = 4;   
656. a[4] = 5;   
657. for (int i=0; i
658.       System.out.println (a);   
659. }   

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16. 在java中解析/读取XML文件

2. view plaincopy to clipboardprint?
3. <?xml version="1.0"?>
4. <students>
5. <student>
6. <name>John</name>
7. <grade>B</grade>
8. <age>12</age>
9. </student>
10. <student>
11. <name>Mary</name>
12. <grade>A</grade>
13. <age>11</age>
14. </student>
15. <student>
16. <name>Simon</name>
17. <grade>A</grade>
18. <age>18</age>
19. </student>
20. </students>
22. <?xml version="1.0"?>
23. <students>
24. <student>
25. <name>John</name>
26. <grade>B</grade>
27. <age>12</age>
28. </student>
29. <student>
30. <name>Mary</name>
31. <grade>A</grade>
32. <age>11</age>
33. </student>
34. <student>
35. <name>Simon</name>
36. <grade>A</grade>
37. <age>18</age>
38. </student>
39. </students>
40. java code to parse above XML.
41. view plaincopy to clipboardprint?
42. package net.viralpatel.java.xmlparser;   
43. import java.io.File;   
44. import javax.xml.parsers.DocumentBuilder;   
45. import javax.xml.parsers.DocumentBuilderFactory;   
46. import org.w3c.dom.Document;   
47. import org.w3c.dom.Element;   
48. import org.w3c.dom.Node;   
49. import org.w3c.dom.NodeList;   
50. public class XMLParser {   
51. public void getAllUserNames(String fileName) {   
52. try {   
53. DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();   
54. DocumentBuilder db = dbf.newDocumentBuilder();   
55. File file = new File(fileName);   
56. if (file.exists()) {   
57. Document doc = db.parse(file);   
58. Element docEle = doc.getDocumentElement();   
59. // Print root element of the document   
60. System.out.println("Root element of the document: "
61. + docEle.getNodeName());   
62. NodeList studentList = docEle.getElementsByTagName("student");   
63. // Print total student elements in document   
64. System.out   
65. .println("Total students: " + studentList.getLength());   
66. if (studentList != null && studentList.getLength() > 0) {   
67. for (int i = 0; i < studentList.getLength(); i++) {   
68. Node node = studentList.item(i);   
69. if (node.getNodeType() == Node.ELEMENT_NODE) {   
70. System.out   
71. .println("=====================");   
72. Element e = (Element) node;   
73. NodeList nodeList = e.getElementsByTagName("name");   
74. System.out.println("Name: "
75. + nodeList.item(0).getChildNodes().item(0)   
76. .getNodeValue());   
77. nodeList = e.getElementsByTagName("grade");   
78. System.out.println("Grade: "
79. + nodeList.item(0).getChildNodes().item(0)   
80. .getNodeValue());   
81. nodeList = e.getElementsByTagName("age");   
82. System.out.println("Age: "
83. + nodeList.item(0).getChildNodes().item(0)   
84. .getNodeValue());   
85. }   
86. }   
87. } else {   
88. System.exit(1);   
89. }   
90. }   
91. } catch (Exception e) {   
92. System.out.println(e);   
93. }   
94. }   
95. public static void main(String[] args) {   
96. XMLParser parser = new XMLParser();   
97. parser.getAllUserNames("c:\\test.xml");   
98. }   
99. }
100. package net.viralpatel.java.xmlparser;
101. import java.io.File;
102. import javax.xml.parsers.DocumentBuilder;
103. import javax.xml.parsers.DocumentBuilderFactory;
104. import org.w3c.dom.Document;
105. import org.w3c.dom.Element;
106. import org.w3c.dom.Node;
107. import org.w3c.dom.NodeList;
108. public class XMLParser {
109. public void getAllUserNames(String fileName) {
110. try {
111. DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
112. DocumentBuilder db = dbf.newDocumentBuilder();
113. File file = new File(fileName);
114. if (file.exists()) {
115. Document doc = db.parse(file);
116. Element docEle = doc.getDocumentElement();
117. // Print root element of the document
118. System.out.println("Root element of the document: "
119. + docEle.getNodeName());
120. NodeList studentList = docEle.getElementsByTagName("student");
121. // Print total student elements in document
122. System.out
123. .println("Total students: " + studentList.getLength());
124. if (studentList != null && studentList.getLength() > 0) {
125. for (int i = 0; i < studentList.getLength(); i++) {
126. Node node = studentList.item(i);
127. if (node.getNodeType() == Node.ELEMENT_NODE) {
128. System.out
129. .println("=====================");
130. Element e = (Element) node;
131. NodeList nodeList = e.getElementsByTagName("name");
132. System.out.println("Name: "
133. + nodeList.item(0).getChildNodes().item(0)
134. .getNodeValue());
135. nodeList = e.getElementsByTagName("grade");
136. System.out.println("Grade: "
137. + nodeList.item(0).getChildNodes().item(0)
138. .getNodeValue());
139. nodeList = e.getElementsByTagName("age");
140. System.out.println("Age: "
141. + nodeList.item(0).getChildNodes().item(0)
142. .getNodeValue());
143. }
144. }
145. } else {
146. System.exit(1);
147. }
148. }
149. } catch (Exception e) {
150. System.out.println(e);
151. }
152. }
153. public static void main(String[] args) {
154. XMLParser parser = new XMLParser();
155. parser.getAllUserNames("c:\\test.xml");
156. }
157. }

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17. 在java中将Array转换成Map

2. view plaincopy to clipboardprint?
3. import java.util.Map;   
4. import org.apache.commons.lang.ArrayUtils;   
5. public class Main {   
6. public static void main(String[] args) {   
7. String[][] countries = { { "United States", "New York" }, { "United Kingdom", "London" },   
8. { "Netherland", "Amsterdam" }, { "Japan", "Tokyo" }, { "France", "Paris" } };   
9. Map countryCapitals = ArrayUtils.toMap(countries);   
10. System.out.println("Capital of Japan is " + countryCapitals.get("Japan"));   
11. System.out.println("Capital of France is " + countryCapitals.get("France"));   
12. }   
13. }
15. import java.util.Map;
16. import org.apache.commons.lang.ArrayUtils;
17. public class Main {
18. public static void main(String[] args) {
19. String[][] countries = { { "United States", "New York" }, { "United Kingdom", "London" },
20. { "Netherland", "Amsterdam" }, { "Japan", "Tokyo" }, { "France", "Paris" } };
21. Map countryCapitals = ArrayUtils.toMap(countries);
22. System.out.println("Capital of Japan is " + countryCapitals.get("Japan"));
23. System.out.println("Capital of France is " + countryCapitals.get("France"));
24. }
25. }

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18. 在java中发送电子邮件

2. view plaincopy to clipboardprint?
3. import javax.mail.*;   
4. import javax.mail.internet.*;   
5. import java.util.*;   
6. public void postMail( String recipients[ ], String subject, String message , String from) throws MessagingException   
7. {   
8. boolean debug = false;   
9. //Set the host smtp address   
10. Properties props = new Properties();   
11. props.put("mail.smtp.host", "smtp.example.com");   
12. // create some properties and get the default Session   
13. Session session = Session.getDefaultInstance(props, null);   
14. session.setDebug(debug);   
15. // create a message   
16. Message msg = new MimeMessage(session);   
17. // set the from and to address   
18. InternetAddress addressFrom = new InternetAddress(from);   
19. msg.setFrom(addressFrom);   
20. InternetAddress[] addressTo = new InternetAddress[recipients.length];   
21. for (int i = 0; i < recipients.length; i++)   
22. {   
23. addressTo = new InternetAddress(recipients);   
24. }   
25. msg.setRecipients(Message.RecipientType.TO, addressTo);   
26. // Optional : You can also set your custom headers in the Email if you Want   
27. msg.addHeader("MyHeaderName", "myHeaderValue");   
28. // Setting the Subject and Content Type   
29. msg.setSubject(subject);   
30. msg.setContent(message, "text/plain");   
31. Transport.send(msg);   
32. }
34. import javax.mail.*;
35. import javax.mail.internet.*;
36. import java.util.*;
37. public void postMail( String recipients[ ], String subject, String message , String from) throws MessagingException
38. {
39. boolean debug = false;
40. //Set the host smtp address
41. Properties props = new Properties();
42. props.put("mail.smtp.host", "smtp.example.com");
43. // create some properties and get the default Session
44. Session session = Session.getDefaultInstance(props, null);
45. session.setDebug(debug);
46. // create a message
47. Message msg = new MimeMessage(session);
48. // set the from and to address
49. InternetAddress addressFrom = new InternetAddress(from);
50. msg.setFrom(addressFrom);
51. InternetAddress[] addressTo = new InternetAddress[recipients.length];
52. for (int i = 0; i < recipients.length; i++)
53. {
54. addressTo = new InternetAddress(recipients);
55. }
56. msg.setRecipients(Message.RecipientType.TO, addressTo);
57. // Optional : You can also set your custom headers in the Email if you Want
58. msg.addHeader("MyHeaderName", "myHeaderValue");
59. // Setting the Subject and Content Type
60. msg.setSubject(subject);
61. msg.setContent(message, "text/plain");
62. Transport.send(msg);
63. }

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19. 使用java发送HTTP请求和提取数据

2. view plaincopy to clipboardprint?
3. import java.io.BufferedReader;   
4. import java.io.InputStreamReader;   
5. import java.net.URL;   
6. public class Main {   
7. public static void main(String[] args)  {   
8. try {   
9. URL my_url = new URL("http://www.viralpatel.net/blogs/");   
10. BufferedReader br = new BufferedReader(new InputStreamReader(my_url.openStream()));   
11. String strTemp = "";   
12. while(null != (strTemp = br.readLine())){   
13. System.out.println(strTemp);   
14. }   
15. } catch (Exception ex) {   
16. ex.printStackTrace();   
17. }   
18. }   
19. }
21. import java.io.BufferedReader;
22. import java.io.InputStreamReader;
23. import java.net.URL;
24. public class Main {
25. public static void main(String[] args)  {
26. try {
27. URL my_url = new URL("http://www.viralpatel.net/blogs/");
28. BufferedReader br = new BufferedReader(new InputStreamReader(my_url.openStream()));
29. String strTemp = "";
30. while(null != (strTemp = br.readLine())){
31. System.out.println(strTemp);
32. }
33. } catch (Exception ex) {
34. ex.printStackTrace();
35. }
36. }
37. }

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20. 在java中调整数组

3. view plaincopy to clipboardprint?
4. /**
5. * Reallocates an array with a new size, and copies the contents
6. * of the old array to the new array.
7. * @param oldArray  the old array, to be reallocated.
8. * @param newSize   the new array size.
9. * @return          A new array with the same contents.
10. */
11. private static Object resizeArray (Object oldArray, int newSize) {   
12. int ldSize = java.lang.reflect.Array.getLength(oldArray);   
13. Class elementType = oldArray.getClass().getComponentType();   
14. Object newArray = java.lang.reflect.Array.newInstance(   
15. elementType,newSize);   
16. int preserveLength = Math.min(oldSize,newSize);   
17. if (preserveLength > 0)   
18. System.arraycopy (oldArray,0,newArray,0,preserveLength);   
19. return newArray;   
20. }   
21. // Test routine for resizeArray().   
22. public static void main (String[] args) {   
23. int[] a = {1,2,3};   
24. a = (int[])resizeArray(a,5);   
25. a[3] = 4;   
26. a[4] = 5;   
27. for (int i=0; i<a.length; i++)   
28. System.out.println (a);   
29. }

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gnwe1990

谢谢楼主分享。